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include/boost/capy/write.hpp

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write.hpp
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boost::capy::task<boost::capy::io_result<unsigned long> > boost::capy::write<boost::capy::test::write_stream, boost::capy::const_buffer>(boost::capy::test::write_stream&, boost::capy::const_buffer) :91 20x 100.0% 44.0% boost::capy::task<boost::capy::io_result<unsigned long> > boost::capy::write<boost::capy::test::write_stream, std::array<boost::capy::const_buffer, 2ul> >(boost::capy::test::write_stream&, std::array<boost::capy::const_buffer, 2ul>) :91 30x 100.0% 44.0%
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1 //
2 // Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com)
3 //
4 // Distributed under the Boost Software License, Version 1.0. (See accompanying
5 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6 //
7 // Official repository: https://github.com/cppalliance/capy
8 //
9
10 #ifndef BOOST_CAPY_WRITE_HPP
11 #define BOOST_CAPY_WRITE_HPP
12
13 #include <boost/capy/detail/config.hpp>
14 #include <boost/capy/io_task.hpp>
15 #include <boost/capy/buffers.hpp>
16 #include <boost/capy/buffers/buffer_slice.hpp>
17 #include <boost/capy/concept/write_stream.hpp>
18 #include <system_error>
19
20 #include <cstddef>
21
22 namespace boost {
23 namespace capy {
24
25 /** Make an awaitable for writing a buffer sequence to a stream.
26
27 @par Await-effects
28
29 Writes the contents of `buffers` to `stream` via awaiting on
30 `stream.write_some` with consecutive portions of data form `buffers`
31 until:
32
33 @li either the full content of @c buffers is processed,
34 @li or a contingency occurs.
35
36
37 @par Await-returns
38
39 An object of type `io_result<std::size_t>` destructuring as `[ec, n]`.
40
41 Upon a contingency, `n` represents the number of bytes written
42 so far.
43
44 Otherwise `n` represents the number of bytes written.
45
46 Contingencies:
47
48 @li Whatever the first contingency is reported from
49 awaiting on @c stream.write_some .
50
51 Notable conditions:
52
53 @li @c cond::canceled — Operation was cancelled,
54 @li @c std::errc::broken_pipe — Peer closed connection.
55
56
57 @par Await-postcondition
58
59 `ec || n == buffer_size(buffers)`.
60
61
62 @par Cancellation
63 Supports cancellation via `stop_token` propagated through the
64 `IoAwaitable` protocol. When cancelled, returns with `cond::canceled`.
65
66 @param stream The stream to write to. If the lifetime of `stream` ends
67 before the coroutine finishes, the behavior is undefined.
68
69 @param buffers The buffer sequence to write. If the lifetime of `buffers` ends
70 before the coroutine finishes, the behavior is undefined.
71
72
73 @par Example
74
75 @code
76 task<> send_response(capy::WriteStream auto& stream, std::string_view body)
77 {
78 auto [ec, n] = co_await capy::write(stream, capy::make_buffer(body));
79 if (ec)
80 throw std::system_error(ec);
81
82 // All bytes written successfully
83 }
84 @endcode
85
86 @return
87
88 @see write_some, WriteStream, ConstBufferSequence
89 */
90 template <WriteStream S, ConstBufferSequence CB>
91 50x auto write(S& stream, CB buffers) -> io_task<std::size_t>
92 {
93 auto consuming = buffer_slice(buffers);
94 std::size_t const total_size = buffer_size(buffers);
95 std::size_t total_written = 0;
96
97 while(total_written < total_size)
98 {
99 auto [ec, n] = co_await stream.write_some(consuming.data());
100 consuming.remove_prefix(n);
101 total_written += n;
102 if(ec)
103 co_return {ec, total_written};
104 }
105
106 co_return {{}, total_written};
107 100x }
108
109 } // namespace capy
110 } // namespace boost
111
112 #endif
113